Muscles of mastication
MUSCULI
MASTICATORII
▪ Lat. masticare = to chew
▪ Embryologically, the muscles of mastication
develop from the first (mandibular) pharyngeal
arch
▪ Movements of the mandible in the
temporomandibular joint, while the rest of the
skull remains stable
▪ origin - from the bones of the neurocranium
(non-movable bones),
insertion - on the mandible (freely movable
bone)
▪ Pinnate structure
▪ Blood supply: maxillary artery (end branch of
ACE)
▪ Nerve supply: mandibular branch of trigeminal
nerve
▪ 4 pairs of muscles
Masseter muscle
- Thick, quadrilateral
muscle, superficially
located – on the side
of the face, anterior
to the parotid
salivary gland
- Divided into
Superficial, middle
and deep portion
- inervation:
n. massetericus
(V3)
lamina spf.
lamina prof.
pars ventralis
pars dorsalis:
l. spf.
l. intermedia
l. prof.
Functional organization of the human masseter muscle.
J.F. Gaudy et al. (2000) Surg Radiol Anat 22:181-190.
Pars superficialis
Pars intermedia
Pars profunda
Origo
the lower edge of the os
zygomaticum up to the
zygomaticotempor suture
Insertio
outer surface of the ramus
mandibulae
lower ½ up to tuberositas
masseterica
Pars spf.
Pars media
Origo
lower edge of anterior 2/3 arcus zygomaticus
Insertio
middle 1/3 of ramus mandibulae
Origo
inner side of arcus zygomat.
deep lamina of temporal fascia
Insertio
outer side of ramus mandibulae (upper ½) visible
as so-called fovea m. zygomaticomandibularis
Pars prof.
Functional organization of the human masseter muscle
www.springerlink.com/index/U007G453650W2163.pdf
Frontal section
p. superficialis
p. intermedia
p. profunda
Bilateral contraction:
The superficial part:
Elevation – closes the
mouth
propulsion
The deep portion:
elevation
Unilateral contraction:
ipsilateral lateropulsion
Function
Pars media et profunda
works together as one unit
▪ The typical pinnate structure
▪ Zones of muscular and aponeurotic attachments
▪ The structure allows spreading the infection
(submasseteric abscess)
The Architecture
▪ Firmly connected with the muscle
▪ From arcus zygomaticus to basis mandibulae
▪ Dorsally merge with fascia parotis (fascia
parotideomasseterica)
▪ Caudally connected with basis mandibulae ->
fascia colli spf.
▪Ventrally attached to the ramus mandibulae
The Masseteric Fascia
Palpation
Palpation of the masseter muscle by having patient clench the teeth
The Superficial Portion The Deep Portion
Temporalis muscle
M. TEMPORALIS
- Lies in fossa temporalis
- Flat muscle
- Fan shape, pinnate
- Covered by
fascia temporalis
- Blood supply.: a. tempor. media (a.tempor.superfic.)
a. tempor. prof. (a.maxillaris)
- inervation: nn. tempor. prof. (V3)
In the long axis of the muscle, a caudally
strengthening central tendon (double pinched
muscle) is formed.
Therefore, some authors divide muscle into :
- part ventrally from the tendon – pars anterior
- part dorsally from the tendon – pars posterior
Origo
- fossa temporalis – planum temporale
ANTERIOR PART: linea temporalis inf. ossis pariet.,
facies temporalis alae majoris ossis sphen.,
adjacent part of os frontale and os parietale
+ inner surface of the deep lamina of the fascia
temporalis
POSTERIOR PART: squama ossis temporalis
Insertio - muscle fibers converge caudally into a strong
tendon
- tendon on the processus coronoideus
- further converges along the line obliqua and
crista temporalis (up to the trig. retromolare)
- also attached to the lig. pterygomandibulare
2 - pars post. (temp.)
2/3, light color, connection
with fascia looser
1 - pars ant. (orbitalis)
1/3, width approx. 3 cm, dark
color, adheres to fascia
temporalis
Detailed description
The temporalis muscle consists of three parts:
superficial
zygomatic
deep portion
The human temporalis muscle: Superficial, deep, and zygomatic ...
onlinelibrary.wiley.com › ... › Journal Home › Vol 22 Issue 6
Origo: temporal aponeurosis, temporal line
Insertion: the coronoid process of the mandible
The Superficial Portion
Origo: superior and medial zygoma and zygomatic
arch
Insertion: coronoid process
Fuse with tendon of the superficial
part of the temporalis muscle and
with the deep masseter portion.
Rostrally interdigitated with the
portion of the deep temporalis part
The Zygomatic Portion
Origo: bony surface of the frontal, sphenoid,
parietal and temporal bones
Insertion: coronoid process
and the ramus of the
mandible, just caudal to the
last molar (retromolar
triangle)
Fibers from deep part interdigitated with the
buccinator and the superior pharyngeal constrictor
The Deep Portion
Function
Contraction bilateral:
- ant. and middle fibers = elevation, propulsion
- Posterior fibers = retropulsion
Contraction unilateral::
kontralateral lateropulsion
Maintains the middle
position of TMJ
Covers the temporal muscle
Origo: superior temporal line
Insertion: zygomatic arch
Has two layers:
1. superficial
inserted into the lateral border of the arch
2. deep
inserted into the medial border of the arch
Between these layers is a small quantity of fat and
attachment of the superficial fibres of the temporal
muscle
The Temporal Fascia
Skull
Palpation
The Anterior Part The Posterior Part
Pterygoid muscles
Medial (Internal)
Pterygoid Muscle
M. pterygoideus
med.
- Internal wing
muscle
- Strong flattened
muscle
- In the infratemporal
fossa
- It is similar to the
masseter on the
inside of the ramus
mandibulae
- Part of the muscle
loop around the
mandible
Caput lat.
smaller
Origo: tuber maxillae
Caput med.
bigger
Origo: fossa pterygoidea, from
the med. surface of lamina later.
proc. pteryg., proc. pyramidalis
ossis palatini
Course of fibers: caudally,
dorsally, later.
Insertio: tuberositas pterygoidea
med. side angulus mandib., part of
ramus mandib. above tuberosity
1 - lateral part
2 - medial part
Inner surface of the
ramus mandibulae
Funktion
Bilateral contraction:
elevation
propulsion
Unilateral contraction:
kontralateral
lateropulsion
The beginning of the muscle is
closer to the midline than the
attachment, so in a one-sided
contraction it pulls the mandible
to the opposite side; plays a
major role in frictional chewing
movements
Some muscle fibres in
area of angulus
mandibulae could be
connected with m.
masseter – then
create a loop around
angulus mandibulae
7 musculo-aponeurotic
layers are making up a
penniform structure
7 5
6 4
3
2
1
The Architecture
Palpation
Difficult
It is performed
simultaneously intra and
extraorally:
Intraorally: at the site of
application of seductive
anesthesia and laterally
Extraorally: med. From
lower edge of ramus
mandibulae
Lateral (External)
Pterygoid Muscle
- Short, thick muscle,
conical in form
- Located in upper
part of infratemporal
fossa, deep to the
temporalis muscle
- Innervation: n.
pteryg. lat. (V3)
- Two separate
heads of origin, they
fuse posteriorly
Origo:
caput sup.
crista infratempor. alae
maj. ossis sphenoidalis
caput inf.
lower ¾ of lat. surface
lamina lat. pr.
pterygoidei
Fibres pass horizontally
backward and laterally
Insertion:
- fovea pterygoidea
(depression in front of
the neck of the condyle)
- joint capsule and
articular disc of the TMJ
(front margin)
Bilateral contraction:
protraction, brings the
lower jaw forward
Depression, opening of
the jaw
- tightens the disc and the
front part of the joint capsule prevents
it from closing
Unilateral contraction:
lateropulsion, it pulls
the jaw to the
contralateral side
Function
Palpation
This muscle is inaccessible to intraoral palpation
Between the medial and lateral pterygoid
muscles
Origo: the base of the skull
Insertion: inner surface of the mandible
The border is reinforced by sphenomandibular
ligament
Contain nerves and vessels
Allow spread of infection
The Interpterygoid Fascia
From the functional viewpoint, some of suprahyoid
muscles pull the mandible caudally and cause the
mandibular depression (mouth opening) –
m.mylohyoideus, venter ant. m. digastrici – and
form the masticatory muscles. They both start on
corpus mandibulae and are innervated by
n.mylohyoideus (V3)